According to a conventional audio coding/decoding technology, users should inactively listen to audio content. Thus, it is required to develop an apparatus and method for coding and decoding audio signals in multi-channels for a plurality of audio objects so that various audio objects can be consumed by controlling audio objects each of which having a different channel according to a user's need, and combining one audio content in various methods.
Conventional spatial audio coding (SAC) is a technology for representing, transmitting and recovering multi-channel audio signals as downmixed mono or stereo signals, and it can transmit multi-channel audio signal of a high-quality at a low bit rate.
However, since the conventional SAC is capable of coding and decoding signals in multi-channels only for one audio object, it cannot code/decode a multi-channel and multi-object audio signals, for example, audio signals for various objects in multi-channels, e.g., mono, stereo and 5.1 channels.
Also, conventional Binaural Cue Coding (BCC) technology can code/decode audio signals for multiple objects. However, since the channels of the audio objects are limited to a mono channel, multi-object audio signals with various channels including the mono channel may not be coded/decoded.
To sum up, since the conventional technologies can code/decode only multi-object audio signals with a single channel or a single-object audio signal with multi-channel, multi-object audio signals with various channels may not be coded/decoded. Therefore, users should inactively listen to audio contents according to the conventional audio coding/decoding technologies.
Accordingly, it is required to develop an apparatus and method for coding and decoding audio signals in various channels for each of multiple audio objects to consume various audio objects by controlling each audio object in mulitple channels, which are different according to a user's need, and combining one audio content according to various methods.
Also, an apparatus and method for converting multi-object audio bitstream into a conventional SAC bitstream and vice versa is required to provide backward compatibility between side information bitstream created in a multi-object audio coder and side information bitstream of a conventional SAC coder/decoder.
As described above, as the apparatus and method for coding and decoding the multi-object audio signal of various channels by individually control a plurality of audio objects with different channels and combining one audio content according to various methods, it is required to develop a multi-channel and the multi-object audio coding and decoding apparatus and method which can perform bitstream conversion to provide backward compatibility with the conventional SAC bitstream, and control each of the multiple audio objects having multi-channels to thereby combine one audio objects in diverse methods.